1. Field of the Invention
The present invention relates to an image reading device which, while conveying an elongated image information support on which a plurality of frame images are recorded, reads the frame images by a line scanner.
2. Description of the Related Art
A technique is known in which frame images recorded on an image information support, e.g., a photographic film, are optically read by a reading sensor such as a CCD, image processing such as enlargement/reduction, various types of correction, and the like are carried out on the digital image data obtained by the reading, and an image is formed on a recording material by laser light which is modulated on the basis of the digital image data which has been subjected to image processing.
In this technique of digitally reading an image frame by an area sensor such as a CCD, in order to realize highly accurate image reading, the frame image is preliminarily read (so-called prescanning), reading conditions corresponding to the density or the like of the frame image are determined (e.g., the amount of light to be irradiated onto the frame image, the charge accumulating time of the CCD, and the like), and reading of the frame image is carried out again under the determined reading conditions (so-called fine scanning).
However, in the case of a photographic film provided with a magnetic recording layer (hereinafter referred to as an APS film), in addition to the image reading, additional operations for processing the magnetic information (reading and writing the magnetic information) are carried out. Accordingly, in the series of film processings, the four steps of reading magnetic information from the magnetic recording layer, writing magnetic information onto the magnetic recording layer, prescanning by using the line sensor, and fine scanning by using the line sensor, are carried out.
Here, the reading speed (the APS film conveying speed) of image reading (fine scanning) by the line scanner differs per image frame. On the other hand, from the standpoint of processing efficiency, it is desirable that fine scanning of the respective image frames and writing of magnetic information are carried out simultaneously. Accordingly, a distance, in the conveying direction of the APS film, between the write position of the magnetic information (the position of the writing head) and the image information scanning position (the reading position of the line scanner) is preferably set to be an integer multiple of the image frame pitch of the film.
However, the distance from the final frame of an APS film to the final end of the film is a predetermined length which is based on manufacturers' standards. Accordingly, in a case such as that described above in which the magnetic information writing head and the line scanner are positioned along the APS film conveying path with an interval therebetween which is an integer multiple of the image frame pitch, there is the possibility that the final image frame of the APS film cannot reach the scanning position of the line scanner, and that reading of the image information of the final image frame may not be possible. (Namely, there is the possibility that the final image frame of the APS film may only be able to reach the position of the magnetic information writing head.)